Controls for fluid pressure system



Sept.17, 1957 c. F. CURL 2,806,745-

CONTROLS FOR FLUID PRESSURE} SYSTEM Filed April 28, 1954 2 Sheets-Sheet 1 INVENTOR CHARLES F. CURL BY 03, V

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CONTROLS FOR FLUID PRESSURE SYSTEM Sept-17, 1957 Filed April 28, 1954 2 Sheets-Sheet 2 INVENTOR CHARLES F. CURL -BY.% 1 f ATI' NEY United States This invention relates to controls for a fluid pressure system, and more particularly to controls for a fluid brake system of a railway train.

Heretofore, fluid pressure systems which have been divided into sections of difierent pressures have been operated by inadequate and slowly responsive control means so that the pressures have not been varied as quickly or as efliciently as necessary. This has been particularly true in the case of air brake systems on railway trains. It is commonly known that a railway train having a large number of cars, and particularly on grades, is subject to slack between some of the cars when brakes on the other cars are applied first. When the brakes are applied by reducing the pressure in the train line, the fluid pressure varies in diflerent sections of the train causing the brakes in the forward cars to be applied first, resulting in the rear cars jamming against the cars in front of them and causing damage not only to the cars themselves, but also to persons and property within the cars.

Particularly troublesome to the railroads have been what is commonly known as riffrafis, which are depressions in the track over which the train must travel. Going downgrade the cars accelerate, but as the engine and forward cars begin their ascent on the upgrade, after having passed the depression, they slow down causing the rear cars, which are still descending the downgrade, to jam into one another. As the engine continues upgrade, it takes out slack between the cars, causing a jerk at the rear of the train, and sometimes causing a drawhead to be pulled from the rear cars. Generally, it is the caboose which receives the most damage.

Several attempts to provide a fluid brake system for a train divided into sections having separate controls have been made, but with unsatisfactory results. These systems have been controlled by a multiplicity of valves and pipes and by inadequately responsive restrictor devices which separate the systems into carrying pressure sections.

An object of this invention is to overcome the disadvantages enumerated and to provide a more eflicient, quickly responsive, complete, and locally operated unitary control means for such a fluid pressure system.

Another object of the invention is to provide a restricted flow device separating the system into different pressure sections which will allow fluid to flow alternately in either direction and will be more quickly responsive to the pressure differential between the sections.

Another object of the invention is to centralize the control of a section of the system so that it may be operated remotely from and independently of the controls of the other section.

A further object of the invention is to provide an emergency exhaut subject to the centralized control system. 1

A further object of the invention is to provide a railway brake'system whereby the brakes on the rear cars may be applied and held independently of the forward cars.

atet O ice Another object of this invention is to provide a railway brake system in which a service or emergency application of the brakes on the rear cars of a train may be made from one of the rear cars or the locomotive.

Another object of the invention is to provide a railway brake system in which the emergency brakes may be applied from either the front or the rear of the train.

A further object of the invention is to provide a railway brake system in which emergency brakes will be applied when a fluid line bursts.

Further objects and advantages of the invention will be apparent from the following description taken in conjunction with the drawing wherein:

Fig. l is a schematic diagram of the invention;

Fig. 2 discloses four positions of the multi-position valves;

Fig. 3 is a vertical section of the equalizer;

Fig. 4 is a section on the lines 1-1 of Fig. 3;

Fig. 5 is an end view of a preferred form of the restricted flow device;

Fig. 6 is a section on the lines 22 of Fig. 5.

Briefly stated, the invention comprises a fluid pressure system divided into two sections by a restricted flow device which contains a pair of check valves, each of which will allow flow in directions opposite to each other. One of these check valves is provided with choke means to allow restricted flow when the pressure differential is small. The section involving the novel means of control, which would be the rear section of a railway train system, has a fluid circuit in parallel with this rear section containing in series a multi-position control valve, a fluid reservoir, and an equalizer. The control valve is also provided with an exhaust and may be separately connected to one or more auxiliary fluid reservoirs. By regulating the multi-position control valve, compressed fluid may be allowed to fill all the reservoirs and the section of the system which it controls. The valve may also exhaust its section of the system, leaving all the reservoirs filled, or emptying any one or several of the reservoirs at the same time. The valve may also be completely closed so that there is no circulation within any of the circuits of the section or with the exhaust. The equalizer in its preferred embodiment is a cylinder containing a reciprocating pressure sensitive valve having an exhaust near one end which is closed by the valve when the pressure in the other end is greater. When this control system is applied to railway brakes, the brakes are released and the system is filled with compressed fluid. The brakes are applied by exhausting the fluid from the reservoir which is in series with the equalizer and the control valve. The exhaustion of the fluid in this reservoir reduces the pressure in the equalizer on the side opposite the exhaust, allowing the valve to open the exhaust and causing a reduction of pressure in the system which activates the brake mechanisms. For emergency braking, all of the fluid reservoirs are sealed off and the remainder of the section is exhausted.

Referring now to the drawings in detail, Fig. l discloses a schematic diagram of the invention in which 10 represents a portion of the section of the fluid pressure system leading from the main source of compressed air which in the case of a railway train would be the engine. The separately controlled section 11 is connected to section it) by a restricted flow device 12 comprising a pair of check valves 13 and 14 allowing flow in opposite directions from each other and connected in parallel circuit. In a railway brake system, the sections 10 and 11 represent the conventional train line or brake pipe, section 10 controlling the forward cars, and section 11 controlling the rear cars. The devices 15 to be actuated by the fluid pressure in section 11 such as railway air brakes are connected to section 11 by pipes 16. Pressure gauges 17 are connected to devices 15 by conduits 18. In a railway brake system, the gauge 17 registers the brake cylinder. pressure. Conduit 19 allows compressed fluid to pass from section 11 to multiposition control valve 20 which is connected to fluid reservoir 21.'by'conduit' 22. and to auxiliary fluid reservoir 23 by conduit 24; Valve 20is also provided with an exhaust port 25.. 'A pressure equalizer 26 is connected'toreservoir 21 by. conduit 27 and to section 11 by conduit 28." Near the bottom end of. the

equalizer 26 is an exhaust port 29. Pressure gauge 30,

registers the fluid pressure in section 11, through conduit 31.

Dual pressure gauge 50. independently registers the pressure in each reservoir 21 andv 23 to whichit is connected by conduit 52' and conduit 51, respectively. The

main purpose of the, reservoir 23 is to indicate the orig-' inal charged pressure;on the gauge 50, when the pressure in the reservoir 21 has been reduced. The gauge 50may be adapted to indicate not only the. original and the reduced pressure but also the pressure diflerential.

Fig. 2 represents four positions of the valve 20 used in controlling the fluid pressure section 11. In position 1, conduits 19, 22, and 24 are open and exhaust port 25 is closed to allow compressed fluid to-enter reservoirs 21 and 23 from conduit19. In position 2, all conduits 19, 22, 24, and the exhaust port 25 areclosed. In position 3, conduit 22 and exhaust port 25 are open and conduits 19 and 24 are closed so that fluid from reservoir 21 may be exhausted. In position 4, conduit 19 and exhaust port 25 are open and conduits 22 and 24 are closed so that fluid may be exhausted directly from section 11 through conduit 19.

A preferred embodiment of pressure in equalizer 26 is shown in Figs. 3 and 4 as a cylinder'having a disc valve 32 capable of reciprocating axially on member 33. As long as the fluid pressure in conduit 27 plus the weight of the disc valve 32 is greater than the fluid'pressure in conduit 23, the disc valve 32 will remain at the'bottom of equalizer 26 and close the exhaust port 29. But when the pressure in conduit 28 exceeds the pressure in conduit 2? plus the Weight of the disc valve 32, the valve 32 will be forced upward, opening the exhaust port 29 until the valve reaches some position of pressure equilibrium 32.

Figs. and 6 disclose a preferred embodiment of the restricted flow device 12 in which the double check valves are incorporated within a block 34 of substantially rectangular cross-section having a primary fluid passage-35 extending through the length of the block 34 and having threaded connection 36 to receive the conduit from section 19 and threaded connection 37 to receive the conduit fromsection 11. Controlling the fluid flow from section 19 to section 11 and located in the primary passage 35 is a check valve 33 retained against seat 39 by coil spring 49 which is seated on bar 41. Another check valve 42 controlling fluidflow from section 11 to section through passage 43, positioned in adjustable spring seat 44, is ret ained by the coil spring 45. against the valve seat 46. Passages 47 and 48 connect the ends of passage 43 to primary passage 35 at positions on each side of the check valve 38 so that the passage 43 and primary'passage 35 are connected in parallel. Aperture 49 in valve 38 is provided as a choke to allow restricted flow in either direction at all times and in particular'when the check valves are closed. It will be seen from the above description that when the pressure in section 10 substantially exceeds thepressure in section 11, the valve 38 will become unseated and allow additional fluid to pass from section 10 to section 11. The more the pressure in section 10 exceeds the pressurein section 11, the greater will be the volume of fluid admitted from section 10 to section 11. Conversely, whenthe pressure/in section 11 exceeds the pressure in section 19, the greater willrbe the volume of fluid admitted from section 11 to section 10 through the check-valve 42. e 1

Various pressure diiferentials between sections 10 and in a train made up of 86 cars, the restricted flow device 12 has operated satisfactorily between the 5th and the 6th cars from the rear.

Each device 15 represents. the conventional combinatic-n, located on each car of'the train, of a triple valve, auxiliary reservoir, and a brake cylinder as illustrated in United States Patent No. 1,923,141 to C. C. Farmer. The brake devices 15 represented in Fig. 1 are each located in one of the cars in the rear section.

It is preferable that the multi-control valve 20, reser voirs 21 and 23, equalizer 26, pressure gauges 30,: 50, and brake cylinder gauge 17, together with their. connecting conduits all be located in the caboose of the train. I

The conduit 19 may connect with any portion of the train line 11 without materially affecting the operation 'of the. multi-control valve 20. In Fig. 1, the conduit 19 is shown. connecting section 11 adjacent the restricted flow device 12, so that. the conduit will pass through all the cars in the rear section before it communicates with the valve 20 in the caboose. To save material, conduit 19 may be connected to section 11 behind the caboose brake conduit 16. The pressure gauge 17 which registers the fluid pressure in the brake cylinder of the caboose and pressure gauge 36 which registers the pressure in the rear section 11 of the train line may be combined into a dual gauge so that the pressures of the brake cylinder and the rear section may be readily compared. The reservoirs 21 and 23 used in actual tests are of equal capacity, each about 1200 cubic inches, although they maybe larger if desired.

. In a preferred method of charging the improved brake system, assuming both sections 10 and 11 of the train line are initially at atmospheric pressure, compressed air at lb. per sq. inch is supplied from the engine to section 10. Since the check valve 14 in the restricted flow device 12 has its spring 45 of approximately one-half pound strength and the strength of spring 40 in check valve 13 is approximately 15 pounds, the compressed air in section 10 will blow the valve 38 from its seat 39 until section 11 obtains a pressure of approximately 55 pounds, at which time the fifteen pound spring 40 will reseat the valve- 38 and compressed air from section 10 will continue to flow through choke 49 into section 11 until the pressures in sections 10 and 11 are equalized. During this charging operation,

valve 20 is in position 1 of Fig. 2 so that reservoir 21 and i 23 are also charged. As compressed air 'flows from restricted flow device 12 through conduit 19, valve 20, conduit 22, reservoir 21 and through conduit 27 into equalizer 26, the pressure will build up above disc valve 32 to equalize the pressure coming through conduit 28 below the valve 32. The valve 32 by virtue of its weight will then slide to the bottom of the equalizer 26,;thusclosing the exhaust 29. Throughout the charging operation, valve 42 remains seated because of the compressed air flowing from section 10 through channel 47 of restricted flow device 12. When the pressures in sections 10 and 11 are equalized, the halfpound spring 45 will keep the valve 42 closed. 1 After the train line sections 10 and 11 are fully charged, they are maintained at the 70 lb. pressure, which is suflicient to release all the brake devices 15.

A service application of the brakes made by the engineer from the locomotive will not be afiectedrby the rear'control system. When a'normal reduction of not more thanrfifg teen pounds is made fromthe'locomotive, thepressure in section 10 will be reduced :to355 pounds causing the brakes onthe forward. cars to-be appliedfirst. This reductionin section will cause valve 42 to be blown, thereby reduc ing the pressure in section 11 and reservoirs 21 and 23 to 55 pounds, causing the brakes of all the cars of the rear section to be applied. During this operation, valve 38 remains seated and valve 20 is still in position 1. After the brakes in all the cars have been applied, the pressure in both sections of the train line is approximately 55 pounds.

Assuming again that both sections of the train line are charged at 70 pounds pressure so that all the brakes are released, a service application of the brakes from the rear section of the train may be made by turning valve 20 to position 3, as shown in Fig. 2, so that approximately a 10 pound, but not greater than 15 pound, reduction is made in section 11. Any greater reduction than this will cause sticky brakes, a condition in which the brake remains engaged against the wheel and is difficult to release. With valve in position 3, compressed air is released from reservoir 21 through conduit 22, valve 20, and exhaust 25, until the pressure in reservoir 21 and in equalizer 26 above the disc valve 32 is reduced to approximately 60 pounds. After a reduction of ten pounds pressure has been made in reservoir 21, valve 20 is moved to lap position (position 2 as shown in Fig. 2) so that the pressure in section 11 will not be reduced below 60 pounds. The pressure in section 11 and conduit 28, still being at 70 pounds, will force the disc valve 32 upward on the member 33 to approximately position 32', causing the exhaust port 29 to open. When the pressure above and below the disc valve is equalized at 60 pounds, the valve 32 will slide to the bottom of the equalizer 26 and close the exhaust port 29. The 60 pound pressure is suflicient to actuate the conventional brake devices 15 so that the cars controlled by section 11 may be slowed down. The valves 42 and 38 in the restricted flow device will remain closed because the pressure in section 10 is still 70 pounds, and the difierential of ten pounds is not sufiicient to open the valve 38 against the fifteen pound spring 46. Compressed air from section 10 will continue to flow through choke 49, but in such small quantities that any excessive air pressure above sixty pounds will be eliminated through exhaust port 29. Consequently the brakes on the rear cars may be applied indefinitely and independently of the brakes on the forward cars controlled by section 10 of the train line. While the brakes are applied in section 11, gauge 17 will register a brake cylinder pressure of approximately pounds. Since the pressure in the brake cylinder is generally 2 /2 times as great as the amount of pressure reduction in the train line, gauge 30 will register 60 pounds, and dual gauge will register 60 pounds for the reservoir 21 and 70 pounds for the reservoir 23, or a pressure differential of ten pounds.

Release of the brakes after a service application by the engineer from the locomotive is conducted and functions in the same manner as the initial charging operation from the locomotive.

Release of the brakes after a service application from the caboose is conducted by returning the valve 28 to position 1 in Fig. 2. The ten pound pressure differential between sections 10 and 11 is eliminated by compressed air flowing from section 10 to section 11 through choke 49 and into brake devices 15 to release the brakes. Since valve 20 is open to conduits 19, 22, and 24, reservoir 21 will be recharged to 70 pounds, increasing the pressure in equalizer 26 above valve 32 to 70 pounds and keeping exhaust port 29 closed. After the release is completed, gauge 17 will read 0 pounds, gauge 36 will read 70 pounds, and dual gauge 5% will read 70 pounds for both reservoirs 21 and 23. Although it is conceivable that if the reservoir 23 were of suficient capacity it would aid in expediting the release of the brakes after a service application, a reservoir 23 of a 1200 cubic inch capacity used in actual practice has not materially assisted in the release of the brakes.

An emergency application is made from the locomotive by reducing the train line pressure in section 10 to zero. Such a reduction will cause check valve 42 to be blown from its seat 46, causing the pressure in section 11 to be rapidly reduced to one-half pound before valve 42 will be reseated. The remaining one-half pound in section 11 will be dissipated through chocke 49 so that the pressure in both sections 10 and 11 will be zero pounds. The same result will be obtained if any portion of the train line in section 10 accidentally bursts.

To make an emergency application from the caboose, valve 20 is turned to position 4 in Fig. 2 so that the train line in section 11 is exhausted directly through conduit 19, valve 20, and port 25 at a rapid rate. As soon as the pressure differential between sections 10 and 11 exceeds 15 pounds, valve 33 is blown from its seat, allowing a rapid reduction of pressure in section 10. When the pressure in section 11 has been reduced to zero pounds and the pressure in section 10 has dropped to 15 pounds, valve 38 will become reseated. The pressure in section 10 will gradually be reduced to zero pounds because of the compressed air flowing through choke 59 and out through exhaust 25. Valve 20 remains in position 4 until it is desired that the brakes be released. A similar result will be obtained if any portion of the train line in section 11 bursts.

After an emergency application from either the locomotive or the caboose, the brakes are released in the same manner as if there had been a service application.

Since the caboose is the best observation point for the braking needs of the rear section of the train, valve 21 reservoirs 21 and 23, equalizer 26, and gauges 17, 3t), and 51) are preferably located in the caboose for operation by the conductor. Gauges 17 and 39 may be incorporated in a dual gauge similar to gauge 56, so that a ready comparison may be made between the train line and brake cylinder pressures.

As a result of tests using this fluid control pressure system in the rear section of a railway train, there have been no draw bars pulled, no hot wheels, nor any damage to equipment or personnel. Furthermore, riding in the caboose or other cars in the rear section of the train has been pleasant and quite comfortable. This control system has been particularly advantageous on long trains having forty or more cars. In a forty to sixty car train, restricted flow device 12 was placed three to four cars from the caboose and used sparingly only in the roughest places. In a 60 to car train, device 12 was placed five to seven cars fi'om the caboose and used often and to great advantage.

The rear car controls do not interfere with the operation of the train from the locomotive, except that after a service application from the rear section, the brakes on the rear cars can not be released from the locomotive.

It will be obvious to those skilled in the art that various changes may be made in the invention, without departing from the spirit and scope thereof, and therefore the invention is not limited by that which is shown in the drawings and described in the specification, but only as indicated in the appended claims.

What is claimed is:

1. An automatic air brake system comprising a train iine and brake mechanisms for individual cars of a train, a restricted flow device dividing the train line into front and rear sections, said device comprising a spring loaded check valve responsive to a pressure differential of approximately 10 to 20 pounds to open said .front section toward the rear section, means associated with said restricted flow device for allowing restricted flow between the front and rear sections when said check valve is closed; a rear section brake control system comprising a multi-position control valve, a fluid reservoir, and a pressure equalizer; said multi-position control valve, comprising means for communicating the fluid reservoir with the rear section of the train line to permit charging and releasing the brake mechanisms in the cars controlled by 7 a the rear section, means for exhausting the fluid reservoir for effecting'a service application of the brake mechanisms of the cars controlled by the rear section, and means for exhausting the rear section of the train line for effecting an emergency application of the brakes of all of the cars in the train; said pressure equalizer comprising a housing communicating with the fluid reservoir and also communicating with the rear section of the train line, and means within said housing for exhausting the rear section of the train line when the pressure in the rear section of the train line exceeds the pressure in the fluid reservoir.

2. An automatic air brake system comprising a train line and brake mechanisms for individual cars of a train, a restricted flow device dividing the train line into front and rear sections, said device comprising a first spring loaded check valve responsive to a pressure ditierential of approximately 10 to 20 pounds to open said front section toward the rear section, a second spring loaded check valve responsive to a pressure differential of approximately one-half pound to open said rear section toward the front section, means associated with said restricted flow device for allowing restricted flow betweenthe front and rear sections when both check valves are closed; a

rear section brake control system comprising a multiposition control valve, a fluid reservoir, and a pressure equalizer; said multi-position control valve comprising means for communicating the fluid reservoir with the rear section of the train line to permit charging and releasing the brake mechanisms in the cars controlled by the rear section, means for exhausting the fluid reservoir 'for eifecting a service application of the brake mechanisms of the cars controlled by the rear section, and

' means for exhausting the rear section of the train line for eflecting an emergency application of thetbrakes of all of the cars inthe train; said pressure equalizer comprising a housing communicating with the fluid reservoir and also communicating with the rear section of the train line and means within said housing for exhausting the rear section of the train line when the pressure in the rear section of the train line exceeds the pressure in the fluid reservoir.

3. The invention according to claim 2 in which the means for. allowing restricted flow between the front and rear sections comprises a choke in said first spring loaded check valve. s V V 4. An automatic air brake system-comprising a' train line and brake mechanisms for individual cars of a train, a restricted flow device dividing the train line into front and rear sections, said" device comprising a spring loaded equalizer; said multi-position control valve comprising, means for communicating the fluid reservoir with the rear section of the train line to permit charging and releasing the brake mechanisms in the cars controlled by the rear sect on, means for exhausting the fluid reservoir for etfecting a service application of the brake mechanisms of the cars controlled by the rearsection, and means for exhausting the rear section of the train line for eflecting an emergency application of the brakes of all of the cars in the train; said pressure equalizer comprising a housing communicating with the fluid reservoir and also communicating with the rear section of the train line, said housing having an exhaust port, a reciprocating valve within said housing being adapted to open said port when the pressure in the rear section of the train line exceeds the pressure in the fluid reservoir and being adapted to close said port when the pressure in the fluid reservoir equals the pressure in the rear section of the train line.

References'cited in the file of this patent 

